A Visual Language for Browsing, Undoing, and Redoing Graphical Interface Commands

We present the concept of an editable graphical history that allows the user to review and modify the actions performed with a graphical user interface. Using a pictorial metaphor borrowed from comic strips, an editable graphical history consists of a series of panels that depict in chronological order the important events in the history of a user's session. We discuss the visual language used in editable graphical histories, and describe Chimera, a graphical editor that generates these histories automatically. The user may scroll through the sequence of panels, reviewing actions at different levels of detail, and selectively undoing, modifying, and redoing previous actions. Chimera's editable graphical histories are constructed from parts of the editor window, the editor control panel, and the editor's pop up menus. Panels indicate both the objects that are modified and the actions performed on them. We describe the heuristics used to determine the objects depicted in each panel, the style in which they are drawn, and how actions are distributed among panels.